AID reassignment method, and apparatus for performing said AID reassignment method

ABSTRACT

Disclosed are an AID reassignment method capable of optimally operating a wireless LAN system, and an apparatus for performing the AID reassignment method. The method comprises the steps of: generating a reconnection request frame for an AID reassignment request; transmitting the generated reconnection request frame to the currently associated access point; and receiving a reconnection response frame including AID reassignment information from the access point. Thus, the AID of the currently associated terminal can be dynamically reassigned according to a change in the characteristics of the terminal, thus operating a wireless LAN system in an optimum manner.

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM FOR PRIORITY

This application is a continuation application of U.S. patentapplication Ser. No. 14/411,302, filed on Dec. 24, 2014, which is aNational Stage of International Patent Application No.PCT/KR2013/005756, filed on Jun. 28, 2013, which claims priority fromKorean Patent Application No. 10-2012-0069980, filed on Jun. 28, 2012 inthe Korean Intellectual Property Office (KIPO), the contents of all ofwhich are incorporated herein by reference in their entirety.

BACKGROUND 1. Technical Field

Example embodiments of the present invention relate in general to awireless communication technology and more specifically to a method ofreassigning an association ID (AID) and an apparatus for performing thesame, which allow an optimal operation of a wireless local area network(WLAN) system according to a change in characteristics of a terminal.

2. Related Art

Various wireless communication techniques are being developed along withthe recent development of an information communication technology. Inparticular, wireless local area network (WLAN) is a technology that canprovide a wireless connection to the Internet in a limited service areasuch as a home or office building using portable terminals, for example,a personal digital assistant (PDA), a laptop computer, and a portablemultimedia player (PMP) based on a wireless frequency technology.

Standards for WLAN technology is developed and standardized by IEEE802.11 working group (WG) in the Institute of Electrical and ElectronicsEngineering (IEEE) 802.11. IEEE 802.11a provides a maximum PHY data rateof 54 Mbps using 5 GHz unlicensed band. IEEE 802.11b provides a maximumPHY data rate of 11 Mbps by using direct sequence spread spectrum (DSSS)in 2.4 GHz band. IEEE 802.11g supports a maximum PHY data rate of 54Mbps by using orthogonal frequency division multiplexing (OFDM) in 2.4GHz band. IEEE 802.11n provides a maximum PHY data rate of 300 Mbpsusing 40 MHz bandwidth with two spatial streams and a maximum PHY datarate of 600 Mbps using 40 MHz bandwidth with four spatial streams.

Along with the wide deployment of WLAN and the diversification ofapplications using WLAN, new WLAN techniques are increasingly needed tosupport higher throughput than IEEE 802.11n. Very high throughput (VHT)WLAN is one of 802.11 WLAN techniques, which is proposed to support adata processing rate of 1 Gbps or more. In particular, IEEE 802.11ac isdeveloped as a standard for providing a very high throughput on the 5GHz band, and IEEE 802.11ad is developed as a standard for providing avery high throughput on the 60 GHz band.

In systems based on the WLAN techniques, an access point assignsindividual association IDs (AIDs) to terminals in the order in which theterminals are associated with the access point. However, when 6,000 ormore terminals are required to be supported (for example, 802.11ah), theaccess point groups terminals having similar characteristics and assignsAIDs to the grouped terminals to perform effective management.

That is, the access point may adjust a network traffic amount and asimultaneous channel access amount by grouping a plurality of terminalin units of pages and setting traffic indication map (TIM) elements atdifferent periods.

When the traffic is overloaded at a TIM setting period, AIDs are neededto be reassigned to change some of terminals in a specific page group toanother page group. In addition, when a service type or a trafficcharacteristic of a terminal is changed, the AID is needed to becorrespondingly reassigned.

In order to the above-described need, research is being conducted on anAID assignment request, but a detailed method for AID assignment is notyet revealed.

SUMMARY

Accordingly, example embodiments of the present invention are providedto substantially obviate one or more problems due to limitations anddisadvantages of the related art.

Example embodiments of the present invention provide a method ofreassigning an association ID (AID), which may optimally operate awireless local area network (WLAN) system according to a change incharacteristics of a terminal.

Example embodiments of the present invention also provide an apparatusfor performing the AID reassignment method.

In some example embodiments, a method of reassigning an association ID(AID), which is performed by a terminal, the method includes generatinga reassociation request frame for an AID reassignment request,transmitting the generated reassociation request frame to a currentlyassociated access point, and receiving a reassociation response frameincluding AID reassignment information from the access point.

The generating of the reassociation request frame for the AIDreassignment request may include generating the reassociation requestframe including an AID reassignment request element.

The AID reassignment request element may include an AID reassignmentcause field.

The AID reassignment cause field may include at least one of servicetype change information, low power mode information, listen intervalchange information, traffic pattern change information, and remainingbattery information.

The reassociation request frame may further include a service typeelement, and when the AID reassignment cause field includes the servicetype change information, the service type element may include a servicetype that is changed based on the service type change information.

The method may further include determining whether the AID reassignmentis needed.

The determining of whether the AID reassignment is needed may includedetermining whether the AID reassignment is needed based on at least oneof traffic pattern information, battery information, and service typeinformation of the terminal.

In other example embodiments, a method of reassigning an association ID(AID), which is performed by an access point, the method includesreceiving a reassociation request frame from a currently associatedterminal, reassigning an AID of the terminal based on the reassociationrequest frame, and transmitting a reassociation response frame includingthe reassigned AID to the terminal.

The receiving of the reassociation request frame from the currentlyassociated terminal may include receiving the reassociation requestframe including an AID reassignment request element from the currentlyassociated terminal.

The AID reassignment request element may include an AID reassignmentcause field.

The reassigning of the AID of the terminal based on the reassociationrequest frame may include checking a current AP address, a service setID (SSID), and the AID reassignment request element included in thereassociation request frame and reassigning the AID of the terminalbased on the AID reassignment cause included in the AID reassignmentrequest element when the reassociation request frame is checked to bethe AID reassignment request.

The reassociation response frame may include at least one of AIDreassignment success information, AID reassignment failure information,and information on the reassigned AID.

In still other example embodiments, a terminal includes a transceivingunit and a processing unit configured to generate a reassociationrequest frame for an association ID (AID) reassignment request; transmitthe generated reassociation request frame to a currently associatedaccess point; and receive a reassociation response frame including AIDreassignment information from the access point.

The processing unit may generate a reassociation request frame includingan AID reassignment request element.

The AID reassignment request element may include an AID reassignmentcause field.

The AID reassignment cause field may include at least one of servicetype change information, low power mode information, listen intervalchange information, traffic pattern change information, and remainingbattery information.

The processing unit may determine whether the AID reassignment is neededbased on at least one of the traffic pattern information, batteryinformation, and service type information of the terminal.

In yet still other example embodiments, an access point includes acommunication unit and a processing unit configured to reassign anassociation ID (AID) of a terminal based on a reassociation requestframe including an AID reassignment request element received from theterminal through the communication unit and transmit a reassociationresponse frame including the reassigned AID to the terminal through thecommunication unit.

The AID reassignment request element may include an AID reassignmentcause field.

The processing unit may check a current AP address, a service set ID(SSID), and the AID reassignment request element included in thereassociation request frame and, when the reassociation request frame ischecked to be an AID reassignment request, reassign the AID of theterminal based on the AID reassignment cause included in the AIDreassignment request element.

BRIEF DESCRIPTION OF DRAWINGS

Example embodiments of the present invention will become more apparentby describing in detail example embodiments of the present inventionwith reference to the accompanying drawings, in which:

FIG. 1 is a conceptual view showing a configuration of an IEEE 802.11wireless local area network (WLAN) system according to an embodiment ofthe present invention;

FIG. 2 is a conceptual view showing an association process for datatransmission in a WLAN system;

FIG. 3 is a conceptual view showing a TIM element format;

FIG. 4 is a conceptual view showing a mechanism of a power save mode ina WLAN system;

FIG. 5 is a conceptual view showing a hierarchical AID structure;

FIG. 6 is a conceptual view showing a TIM element that is set atdifferent periods from a grouped page;

FIG. 7 is a conceptual view showing a reassociation request framestructure;

FIG. 8 is a flowchart showing a TIM reassignment method performed by aterminal according to an embodiment of the present invention;

FIG. 9 is a conceptual view showing a reassociation request framestructure according to an embodiment of the present invention;

FIG. 10 is a conceptual view showing an AID reassignment request elementformat according to an embodiment of the present invention;

FIG. 11 is a conceptual view showing an AID reassignment cause fieldaccording to an embodiment of the present invention;

FIG. 12 is a conceptual view showing a service type element formataccording to an embodiment of the present invention;

FIG. 13 is a flowchart showing a TIM reassignment method performed by anaccess point according to an embodiment of the present invention;

FIG. 14 is a conceptual view showing a reassignment response framestructure according to an embodiment of the present invention;

FIG. 15 is a view showing a configuration of a terminal that performs anAID reassignment method according to an embodiment of the presentinvention; and

FIG. 16 is a view showing a configuration of a terminal that performs anAID reassignment method according to an embodiment of the presentinvention.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Since the present invention may be variously modified and have severalexemplary embodiments, specific exemplary embodiments will be shown inthe accompanying drawings and be described in detail in a detaileddescription.

However, it should be understood that the particular embodiments are notintended to limit the present disclosure to specific forms, but ratherthe present disclosure is meant to cover all modification, similarities,and alternatives which are included in the spirit and scope of thepresent disclosure.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first component may be designatedas a second component, and similarly, the second component may bedesignated as the second component. The use of the term of ‘and/or’means that combination of a plurality of related and described items orone items among a plurality of related and described items is included.

When it is mentioned that a certain component is “coupled with” or“connected with” another component, it may be understood that anothercomponent can exist between the two components although the componentcan be directly coupled or connected with the another component.Meanwhile, when it is mentioned that a certain component is “directlycoupled with” or “directly connected with” another component, it has tobe understood that another component does not exist between the twocomponents.

In the following description, the technical terms are used only forexplaining a specific exemplary embodiment while not limiting thepresent disclosure. Singular forms used herein are intended to includeplural forms unless explicitly indicated otherwise. It will be furtherunderstood that the terms “comprises,” “comprising,” “includes,” and/or“including” when used herein, specify the presence of stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or a combinationthereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. Terms suchas terms that are generally used and have been in dictionaries should beconstrued as having meanings matched with contextual meanings in theart. In this description, unless defined clearly, terms are not ideally,excessively construed as formal meanings.

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Indescribing the invention, in order to facilitate the entireunderstanding of the invention, like numbers refer to like elementsthroughout the description of the figures and the repetitive descriptionthereof will be omitted.

Throughout this specification, a station (hereinafter also referred toas an STA) is any functional medium including a medium access control(MAC) and wireless-medium physical layer (PHY) interface conforming tothe IEEE 802.11 standard. The STA may include an access point (AP) STAand non-AP STA. The AP STA may be simply referred to as an access point(hereinafter also referred to as an AP), and the non-AP STA is simplyreferred to as a terminal.

The STA includes a processor and a transceiver, and may further includea user interface, a display device, and so on. The processor is afunctional unit devised to generate a frame to be transmitted through awireless network or to process a frame received through the wirelessnetwork, and performs various functions to control the STA. Thetransceiver is functionally connected to the processor and is afunctional unit devised to transmit and receive a frame for the STAthrough the wireless network.

The AP may be called a convergence controller, a base station (BS), anode-B, an eNode0B, a base transceiver system, or a site controller, andmay include some or all of functions thereof.

The terminal may be called a user equipment (UE), a mobile station (MS),a user terminal (UT), a wireless terminal, an access terminal (AT), asubscriber unit, a subscriber station (SS), a wireless device, awireless communication device, a wireless transmit/receive unit (WTRU),a mobile node, a mobile, or the like. Examples of the terminal mayinclude, but are not limited to, a cellular phone, a smart phone with awireless communication function, a personal digital assistant (PDA) witha wireless communication function, a wireless modem, a portable computerwith a wireless communication function, an imaging apparatus such as adigital camera with a wireless communication function, a gamingapparatus with a wireless communication function, a home appliance forstoring and playing music files with a wireless communication function,an Internet home appliance capable of wireless Internet connection andbrowsing as well as portable units or terminals incorporatingcombinations of the functions.

FIG. 1 is a conceptual view showing a configuration of an IEEE 802.11WLAN system according to an embodiment of the present invention.

Referring to FIG. 1, the IEEE 802.11 WLAN system includes at least onebasic service set (BSS). The BBS denotes a set of stations STA 1, STA 2(AP 1), STA 3, STA 4, STA 5 (AP 2) that may be successfully synchronizedto communicate with one another, but does not denote a certain region.

The BBS may be classified into an infrastructure BSS and an independentBSS (IBSS). BBS 1 and BBS 2 denote the infrastructure BSS. BBS 1 mayinclude a terminal STA 1, an access point STA 2 (AP 1) that provides adistribution service, and a distribution system (DS) that connects aplurality of access points STA 2 (AP 1) and STA 5 (AP 2). In BSS 1, theaccess point STA 2 (AP 1) manages the terminal STA 1.

BBS 2 may include the terminals STA 3 and STA 4, an access point STA 5(AP 2) that provides a distribution service, and a distribution systemthat connects the plurality of access points STA 2 (AP 1) and STA 5 (AP2). In BSS 2, the access point STA 5 (AP 2) manages the terminals STA 3and STA 4.

The independent BSS (IBSS) is a BSS that operates in an ad-hoc mode.Since the IBSS does not include an access point, there is no centralizedmanagement entity for performing a central management function. That is,in the IBSS, terminals are managed in a distributed manner. The IBSS isa self-contained network, in which all terminals may be mobile terminalsand may be disallowed to access the distribution system (DS).

The access points STA 2 (AP 1) and STA 5 (AP 2) provide a connection tothe DS through a wireless medium for the associated terminals STA 1, STA3 and STA 4. In BSS 1 or BSS 2, generally, a communication between theterminals STA 1, STA 3, and STA 4 is made through the access points STA2 (AP 1) and STA 5 (AP 2). However, when a direct link is established, adirect communication between the terminals STA 1, STA 3, and STA 4 isenabled.

A plurality of infrastructure BBSs may be interconnected through the DS.The plurality of BBSs connected to each other through the DS is calledan extended service set (ESS). STAs included in the ESS may communicatewith each other, and within the same ESS, a terminal may move from oneBSS to another BSS while communicating in a seamless manner.

The DS is a mechanism in which one AP communicates with another AP. Byusing the DS, an AP may transmit a frame to terminals that is associatedwith a BSS managed by the AP, or transmit a frame to a terminal that hasmoved to another BSS. In addition, the AP may transmit and receive aframe to and from an external network such as a wired network. The DS isnot necessarily a network and has no limitation in its form as long as apredetermined distribution service specified in the IEEE 802.11 standardcan be provided. For example, the DS may be a wireless network such as amesh network, or may be a physical structure for interconnecting APs.

An AID reassignment method according to an embodiment of the presentinvention, which will be described below, may be applied to the aboveIEEE 802.11 WLAN system and also various networks such as a wirelesspersonal area network (WPAN), a wireless body area network (WBAN), andso on.

FIG. 2 is a conceptual view showing an association process for datatransmission in a WLAN system.

In order for a terminal STA to transmit and receive data in aninfrastructure BSS, first, the terminal STA should be associated with anAP.

Referring to FIG. 2, the association process of the terminal STA in theinfrastructure BSS may include: 1) probe step of probing an AP, 2)authentication step of authenticating the probed AP, and 3) associationstep of associating with the authenticated AP.

First, the terminal STA may probe neighboring APs through the probeprocess. The probe process includes a passive scanning method and anactive scanning method. The passive scanning method may be performed byoverhearing beacons that are transmitted by the neighboring APs. On theother hand, the active scanning method may be performed by broadcastinga probe request frame. Upon receiving the probe request frame, the APmay transmit a probe response frame corresponding to the probe requestframe to the terminal STA. The terminal STA may check the presence ofthe neighboring APs by receiving the probe response frame.

Subsequently, the terminal STA performs authentication with the probedAPs, and may perform the authentication with the plurality of APs. Anauthentication algorithm conforming to the IEEE 802.11 standard includesan open system algorithm that exchanges two authentication frames and ashared key algorithm that exchanges four authentication frames. Througha process of exchanging the authentication request frame and theauthentication response frame based on the authentication algorithm, theterminal STA may perform authentication with the AP.

Last, the terminal STA selects one AP from among the authenticatedplurality of APs and performs an association process with the selectedAP. That is, the terminal STA transmits an association request frame tothe selected AP. Upon receiving the association request frame, the APtransmits the terminal STA to an association response framecorresponding to the association request frame. As such, through theprocess of exchanging the association request frame and the associationresponse frame, the terminal STA may perform the association processwith the AP.

FIG. 3 is a block diagram showing an element of a traffic indication map(TIM) included in a beacon according to an embodiment of the presentinvention.

In the IEEE 802.11 WLAN system, when there is data to be transmitted tothe terminal, the AP notifies the terminal that there is data to betransmitted using a TIM in a beacon frame that is periodicallytransmitted.

Referring to FIG. 3, the TIM includes an element ID field, a lengthfield, a delivery traffic indication message (DTIM) count field, a DTIMperiod field, a bitmap control field, and a partial virtual bitmapfield.

The length field indicates a length of an information field. The DTIMcount field indicates the number of beacons before the DTIM. When a DTIMcount is 0, a current TIM is the DTIM. The DTIM count field is composedof 1 octet. The DTIM period field indicates the number of beaconintervals between consecutive DTIMs. If all TIMs are the DTIMs, a valueof the DTIM period field is 1. The DTIM period field is composed of 1octet.

The bitmap control field is composed of 1 octet, and a bit number 0 ofthe bitmap control field denotes a traffic indicator bit that isassociated with an association ID (AID) 0. When the bit is set as 1 andthe value of the DTIM count field is 0, it can be seen that at least onemulticast or broadcast frame is buffered in the AP. The remaining 7 bitsof the bitmap control field form a bitmap offset.

Since the length field of the TIM element format is 1 octet, the partialvirtual bitmap may have up to 251 octets, which may represent a total of2,007 (8×251−1) terminals.

In addition, each bit of the partial virtual bitmap field corresponds toa traffic that is buffered for a specific terminal. In a case in whichan AID of any terminal is N, a bit number N of the partial virtualbitmap field is set as 0 when there is no buffered traffic and the bitnumber N of the partial virtual bitmap field is set as 1 when there isbuffered traffic.

FIG. 4 is a conceptual view showing a data transmission process of anaccess point according to an embodiment of the present invention.

Referring to FIG. 4, the AP broadcasts a beacon periodically and maybroadcast a beacon including the DTIM at every 3 beacon intervals. Theterminals STA 1 and STA2 periodically wake up from a power save mode(PSM) and receive the beacon, and check the TIM or DTIM included in thebeacon to determine whether the data to be transmitted to the terminalsis buffered in the AP. In this case, when there is the buffered data,the terminals STA 1 and STA 2 maintain awake and receive the data fromthe AP. When there is no buffered data, the terminals STA 1 and STA 2return to the PSM (that is, a doze state).

That is, when a bit in the TIM corresponding to an AID of the terminalSTA 1 or STA 2 is set as 1, the terminal STA 1 or STA 2 transmits, tothe AP, a power save (PS)-Poll frame (or a trigger frame) that informsthe AP that the terminal STA is awake and ready to receive data. The APmay determine that the terminal STA 1 or STA 2 is ready to receive thedata by receiving the PS-Poll frame and then may transmit the data or anacknowledgement (ACK) to the terminal STA 1 or STA 2. When the APtransmits the ACK to the terminal STA 1 or STA 2, the AP transmits datato the terminal STA 1 or STA 2 at an appropriate time. On the otherhand, when the bit in the TIM corresponding to the AID of the terminalSTA 1 or STA 2 is set as 0, the terminal STA 1 or STA 2 returns to thePSM.

FIG. 5 is a conceptual view showing a hierarchical AID structure, FIG. 6is a conceptual view showing a TIM element that is set at differentperiods from a grouped page, and FIG. 7 is a conceptual view showing areassociation request frame structure.

Referring to FIG. 5, the hierarchical AID structure may include a pageID, a block index, and an STA bit position index in a sub-block.

Through the above-described hierarchical AID structure, 2,007 terminalsor more may be represented and managed as a TIM bitmap.

Referring to FIG. 6, the AP groups a plurality of terminals in units ofpages to set a TIM element at different periods according tocharacteristics of a terminal.

For example, if terminals belonging to Page 1 have a small amount oftraffic, the TIM element is set to the DTIM beacon for the terminalsbelonging to Page 1. In addition, if terminals belonging to Page 2 havea large amount of traffic, the TIM element may be set to every beaconfor the terminals belong to Page 2, thus simultaneously controlling theamount of traffic and the amount of channel connection.

However, the AID of the terminal is needed to be reassigned when aservice type of the terminal that is grouped in units of pages ischanged (for example, the terminal has a different traffic pattern),when a remaining battery life of the terminal is changed, or when alisten interval is needed to be changed.

Typically, the terminal uses the reassociation request frame as shown inFIG. 7 to reassign an AID of the terminal. However, generally, thereassociation request frame shown in FIG. 7 is a frame that istransmitted by the terminal to connect to an AP of a different basicservice set (BSS) in an extended service set (ESS), That is, when theterminal requests an AID reassociation to the currently associatedaccess point, the terminal does not have to transmit a reassociationrequest frame including all information elements as shown in FIG. 7.

FIG. 8 is a flowchart showing a TIM reassignment method performed by aterminal according to an embodiment of the present invention.

Referring to FIG. 8, the terminal 100 determines whether the AIDreassignment is currently needed (S810).

Here, the terminal 100 may determine whether the AID reassignment isneeded based on traffic pattern information, battery information, andservice type information of the terminal 100. For example, when atransmission traffic amount is significantly reduced, or when aremaining battery life is less than a predetermined amount, the terminaldetermines that the AID reassignment is needed to wake up at longerintervals than before.

When it is determined through operation S810 that the AID reassignmentis needed, the terminal 100 generates a reassociation request frameincluding an AID reassignment request element (S820).

Here, the terminal 100 generates a reassociation request frame includingan AID reassignment request element. In addition, since thereassociation request frame is a frame that is transmitted to acurrently associated AP, the reassociation request frame may include acapability field, a listen interval field, a current AP address field, aservice set identifier (SSID) field, a supported rates field, and theAID reassignment request element.

In addition, the AID reassignment request element may include an elementID field, a length field, and an AID reassignment cause field. Here, theAID reassignment cause field may include service type changeinformation, low power mode information, listen interval changeinformation, traffic pattern change information, and remaining batteryinformation.

In addition, the reassociation request frame may further include aservice type element. As such, when the reassociation request framefurther includes the service type element, the terminal 100 may add, tothe service type element, a service type that is changed based on theservice type change information of the terminal 100 included in the AIDreassignment cause field.

The terminal 100 transmits the reassociation request frame generatedthrough operation S820 to a currently associated AP (S830).

Subsequently, the terminal 100 receives, from the AP, a reassignmentresponse frame including the reassigned AID as a response to thereassociation request frame that is transmitted through operation S830(S840).

The above description of the AID reassignment method according to anembodiment of the present invention has exemplified the AID reassignmentcause in a case in which the service type is changed, the terminal ischanged to a low power mode according to a remaining batter situation,or the listen interval is needed to be changed. However, in anotherembodiment of the present invention, the AID reassignment cause is notlimited as long as the gist of the present invention is not impaired.

The above-described reassociation request frame structure, an AIDreassignment request element format, an AID reassignment cause field,and a service type element format will be described below with referenceto FIGS. 9 to 12.

FIG. 9 is a conceptual view showing a reassociation request framestructure according to an embodiment of the present invention, FIG. 10is a conceptual view showing an AID reassignment request element formataccording to an embodiment of the present invention, FIG. 11 is aconceptual view showing an AID reassignment cause field according to anembodiment of the present invention, and FIG. 12 is a conceptual viewshowing a service type element format according to an embodiment of thepresent invention.

Referring to FIG. 9, when it is determined that the reassignment of theAID of the terminal 100 is needed, the terminal 100 transmits areassociation request frame to the currently associated AP 200.

Here, since the AP 200 is the currently associated AP 200, an extendedsupported rates element, a power capability element, a supportedchannels element, a robust security network (RSN) element, a quality ofservice (QoS) capability element, an RM enabled capabilities element,and a mobility domain element may be excluded from the existingreassociation request frame.

In addition, the reassociation request frame that is transmitted by theterminal 100 to the AP 200 may include a capability element, a listeninterval element, a current AP address element, an SSID element, and asupported rates element, and may additionally include an AIDreassignment request element and a service type element to request AIDreassignment.

Referring to FIG. 10, the AID reassignment request element may include 1octet element ID field, 1 octet length field, and 1 octet AIDreassignment cause field.

In particular, as described in FIG. 11, the cause for requesting the AIDreassignment may be represented in units of bits in the AID reassignmentcause field.

Here, the AID reassignment cause field may include cases in which (1) aservice type is changed, that is, a service type of an application layeris changed (for example, the change of the traffic pattern), (2) theterminal is changed to a low power mode according to a remaining batterylife, and (3) the listen interval is needed to be changed. In addition,the AID reassignment cause field may additionally include any case whenthe AID is needed to be reassigned.

Referring to FIG. 12, when the service type is changed, an AIDreassignment cause may add the changed service type to the service typeelement among the reassociation request frame shown in FIG. 9.

Here, the service type element may include an element ID, a length, anda service type.

FIG. 13 is a flowchart showing a TIM reassignment method performed by anaccess point according to an embodiment of the present invention, andFIG. 14 is a conceptual view showing a reassignment response framestructure according to an embodiment of the present invention.

Referring to FIG. 13, the AP 200 receives a reassociation request frameincluding the AID reassignment request element from the terminal 100(S1310).

Here, the AID reassignment request element may include an AIDreassignment cause field that represents a cause for requesting the AIDreassignment.

The AID reassignment cause field may include service type changeinformation, low power mode information, listen interval changeinformation, traffic pattern change information, and remaining batteryinformation.

The AP 200 checks an AP address element, an SSID element, and an AIDreassignment request element, which are included in the reassociationrequest frame received through operation S1310 (S1320) and determineswhether the received reassociation request frame is checked to be an AIDreassignment request (S1330).

Here, the AP 200 may check that the terminal 100 is the currentlyassociated terminal through the check of the AP address and the SSID andmay determine whether the reassociation request frame is an AIDreassignment request through the check of the AID reassignment requestelement.

When the reassociation request frame received through operation S1330 isan AID reassignment request, the AP 200 reassigns an AID of the terminal100 based on an AID assignment cause included in the AID reassignmentrequest element (S1340).

Specifically, the AP 200 may reassign the AID such that the terminal 100wakes up at every beacon when the AID assignment cause is that theamount of traffic of the terminal 100 increases. On the other hand, whenthe amount of traffic of the terminal 100 decreases, the AP 200 mayreassign the AID such that the terminal 100 wakes up at longer intervalsthan before. Alternatively, when the remaining batter is almost empty,or when the listen interval is needed to be long, the AP 200 mayreassign the AID such that the terminal 100 wakes up at longer intervalsthan before.

Here, the AP 200 may add the AID reassignment result to the reassignmentresponse frame shown in FIG. 7. That is, the AP 200 may add a success orfailure of the AID reassignment succeeds or fails to the status code,and may add the reassigned AID value to the AID field.

Subsequently, the AP 200 transmits, to the terminal 100, thereassociation response frame including the AID that is reassignedthrough operation S1340 (S1350).

In the AID reassignment method according to an embodiment of the presentinvention, it is possible to add some fields to the reassociationrequest frame and dynamically reassign the AID of the currentlyassociated terminal to optimally operate a WLAN system.

Elements to be described below are elements defined not by physicalproperties but by functional properties. Thus, each element may bedefined by its function. Each element may be implemented as hardwareand/or a program code and a processing unit for performing its function.The functions of two or more elements may be implemented to be includedin one element.

Accordingly, it should be noted that names of elements in an embodimentto be described below are not given to physically classify the elementsbut given to imply representative functions performed by the elements,and the technical spirit of the present invention is not limited by thenames of the elements.

FIG. 15 is a view showing a configuration of a terminal that performs anAID reassignment method according to an embodiment of the presentinvention.

Referring to FIG. 15, the terminal 100 according to an embodiment of thepresent invention may include a transceiving unit 110 and a processingunit 120.

The transceiving unit 110 may perform communication with the AP 200 oranother terminal based on a control of the processing unit 120.

The processing unit 120 determines whether the AID reassignment isneeded.

Here, the processing unit 120 may determine whether the AID reassignmentis needed based on the traffic pattern information, battery information,and service type information of the terminal 100.

In addition, when the AID reassignment is determined to be needed, theprocessing unit generates the reassociation request frame including theAID reassignment request element.

Specifically, the processing unit 120 generates a reassociation requestframe including an AID reassignment request element.

Here, since the reassociation request frame is a frame that istransmitted to a currently associated AP 200, the reassociation requestframe may include a capability field, a listen interval field, a currentAP address field, a service set identifier (SSID) field, a supportedrates field, and the AID reassignment request element.

In addition, the AID reassignment request element may include an AIDreassignment cause field. Here, the AID reassignment cause field mayinclude service type change information, low power mode information,listen interval change information, traffic pattern change information,and remaining battery information.

In addition, when the reassociation request frame includes the servicetype element, the processing unit 120 may add, to the service typeelement, to a service type that is changed based on the service typechange information of the terminal 100 included in the AID reassignmentcause field.

The processing unit 120 transmits a generated reassociation requestframe to the currently associated AP 200 through the transceiving unit110.

Furthermore, the processing unit 120 receives a reassociation responseframe including the AID reassigned from the AP 200 through thetransceiving unit 110.

The above description of the terminal that performs the AID reassignmentmethod according to an embodiment of the present invention hasexemplified the AID reassignment cause in a case in which the servicetype is changed, the terminal is changed to a low power mode accordingto a remaining batter situation, or the listen interval is needed to bechanged. However, in another embodiment of the present invention, theAID reassignment cause is not limited as long as the gist of the presentinvention is not impaired.

FIG. 16 is a view showing a configuration of a terminal that performs anAID reassignment method according to an embodiment of the presentinvention.

Referring to FIG. 16, the AP 200 according to an embodiment of thepresent invention may include a communication unit 210 and a processingunit 220.

The communication unit 210 may perform communication with nearbyterminals based on a control of the processing unit 220.

The processing unit 220 receives the reassociation request frameincluding the AID reassignment request element from the terminal 100through the communication unit 210.

Here, the AID reassignment request element may include an AIDreassociation cause field that represents a cause to request the AIDreassignment, and the AID reassignment cause field may include servicetype change information, low power mode information, listen intervalchange information, traffic pattern change information, and remainingbattery information.

The processing unit 220 determines whether the received reassociationrequest frame is the AID reassignment request.

Here, the processing unit 220 may check that the terminal 100 is thecurrently associated terminal through the check of the AP address andthe SSID and may determine whether the reassociation request frame is anAID reassignment request through the check of the AID reassignmentrequest element.

When the received reassociation request frame is an AID reassignmentrequest, the processing unit 220 reassigns an AID of the terminal 100based on an AID assignment cause included in the AID reassignmentrequest element and generates a reassociation response frame includingthe reassigned AID.

Here, the processing unit 220 may add a success or failure of the AIDreassignment succeeds or fails to the status code among thereassociation response frame, and may add the reassigned AID value tothe AID field.

In addition, the processing unit 220 transmits the reassociationresponse frame including the reassigned AID to the terminal 100 throughthe communication unit 210.

In the AP that performs the AID reassignment method according to anembodiment of the present invention, it is possible to add some fieldsto the reassociation request frame and dynamically reassign the AID ofthe currently associated terminal to optimally operate a WLAN system.

According to the AID reassignment method and the apparatus that performsthe AID reassignment method according to an embodiment of the presentinvention may include generating a reassociation request frame by addingan AID reassociation request element when the reassignment of an AID toa terminal is needed, transmitting the generated reassociation requestframe to a currently associated access point, and receiving areassociation response frame including AID reassignment information fromthe access point.

Accordingly, the AID of the currently associated terminal may bedynamically reassigned according to a change in characteristics of theterminal to optimally operate a WLAN system.

While the example embodiments of the present invention and theiradvantages have been described in detail, it should be understood thatvarious changes, substitutions and alterations may be made hereinwithout departing from the scope of the invention.

What is claimed is:
 1. A method by a terminal for performing an association ID (AID) reassignment request, the method comprising: establishing, by the terminal, an association with an access point, wherein an AID is assigned to a station by establishing the association; generating, by the terminal to which a first AID has been assigned by the access point with which the terminal is currently associated, a request frame for an AID reassignment request; transmitting the generated request frame to the access point with which the terminal is currently associated; and receiving a response frame including information on a second AID from the access point with which the terminal is currently associated, wherein the second AID different from the first AID is used as a new AID of the terminal, wherein the request frame includes first information indicating whether service type information is included in the request frame or not, and comprises service type information of the terminal according to the first information, and wherein the AID reassignment request is performed when a service type of the terminal being changed.
 2. The method of claim 1, wherein the request frame includes an AID reassignment request element.
 3. The method of claim 1, wherein the request frame includes second information indicating whether listen interval information is included in the request frame or not, and comprises listen interval information of the terminal according to the second information.
 4. The method of claim 1, wherein the AID reassignment request is performed when a listen interval of the terminal being changed.
 5. The method of claim 1, wherein the request frame is a reassociation request frame, and the response frame is a reassociation response frame.
 6. The method of claim 1, wherein the request frame is an AID assignment request frame for AID change, and the response frame is an AID assignment response frame for AID change.
 7. A method by an access point for performing an association ID (AID) reassignment, the method comprising: establishing, by the access point, an association with a station, wherein an AID is assigned to the station by establishing the association; receiving, from a terminal which is currently associated with the access point and a first AID having been assigned to the terminal by the access point, a request frame for AID reassignment request; and transmitting a response frame including information on a second AID to the terminal, wherein the second AID different from the first AID is used as a new AID of the terminal, wherein the request frame includes first information indicating whether service type information is included in the request frame or not, and comprises service type information of the terminal according to the first information, and wherein the AID reassignment request is performed when a service type of the terminal being changed.
 8. The method of claim 7, wherein the request frame includes an AID reassignment request element.
 9. The method of claim 7, wherein the request frame includes second information indicating whether listen interval information is included in the request frame or not, and comprises listen interval information of the terminal according to the second information.
 10. The method of claim 7, wherein the AID reassignment request is performed when a listen interval of the terminal being changed.
 11. The method of claim 7, wherein the request frame is a reassociation request frame, and the response frame is a reassociation response frame.
 12. The method of claim 7, wherein the request frame is an AID assignment request frame for AID change, and the response frame is an AID assignment response frame for AID change.
 13. A terminal for performing an association ID (AID) reassignment request, the terminal comprising: a transceiver; and a processor; wherein the processor is configured to: establish, by the terminal, an association with an access point, wherein an AID is assigned to a station by establishing the association; generate, when a first AID has been assigned to the terminal by the access point with which the terminal is currently associated, a request frame for an AID reassignment request; transmit, using the transceiver, the generated request frame to the access point with which the terminal is currently associated; and receive, using the transceiver, a response frame including information on a second AID from the access point with which the terminal is currently associated, wherein the second AID different from the first AID is used as a new AID of the terminal, wherein the request frame includes first information indicating whether service type information is included in the request frame or not, and comprises service type information of the terminal according to the first information, and wherein the AID reassignment request is performed when a service type of the terminal being changed.
 14. An access point for performing an association ID (AID) reassignment, the access point comprising: a transceiver; and a processor; wherein the processor is configured to: establish, by the access point, an association with a station, wherein an AID is assigned to the station by establishing the association; receive, using the transceiver, from a terminal which is currently associated with the access point and a first AID having been assigned to the terminal by the access point, a request frame for AID reassignment request; and transmit, using the transceiver, a response frame including information on a second AID to the terminal, wherein the second AID different from the first AID is used as a new AID of the terminal, wherein the request frame includes first information indicating whether service type information is included in the request frame or not, and comprises service type information of the terminal according to the first information, and wherein the AID reassignment request is performed when a service type of the terminal being changed.
 15. The access point of claim 14, wherein the request frame includes an AID reassignment request element.
 16. The access point of claim 14, wherein the request frame includes second information indicating whether listen interval information is included in the request frame or not, and comprises listen interval information of the terminal according to the second information.
 17. The access point of claim 14, wherein the AID reassignment request is performed when a listen interval of the terminal being changed.
 18. The access point of claim 14, wherein the request frame is a reassociation request frame, and the response frame is a reassociation response frame.
 19. The access point of claim 14, wherein the request frame is an AID assignment request frame for AID change, and the response frame is an AID assignment response frame for AID change. 